the error code 5C10 indicates a mainboard failure requiring a service of the unithowever, you may try the below intermediate stepsfirst of all please turn off the unit....unplug the power cablenow remove the cartridge...manually slide the carriage assembly\ printhead back and forthalso clean the rail against which the assembly slides with a tissue ensuring that there is no ink residue on itclean the golden contacts of the cartridges and the printhead with a cotton swab dipped in little alcoholonce done turn the unit back on and checkif still the error code flashes its means that the mainboard has faulted and would need to be servicedif the unit is within warranty cover, please call up Canon at 1-800-OK-CANON,1-800-652-2666 to arrange for a servicehowever, in case the unit is out of warranty....then you may take a service quote from a local repair store and check as usually a new unit would be more cost effective than getting this one serviced....let me know if you have any queries....